Remove and discard the outer leaves and core from the cabbage.
Shred the cabbage using a food processor or hand grater.
Combine the cabbage, carrots, and daikon radish in a large bowl.
Chop the green onions and add them to the bowl
Combine the garlic, ginger, and fish sauce in a food processor or a blender and process until finely minced.
Add the garlic mixture, chili powder, and salt to the vegetable mixture and toss gently but thoroughly to combine. You can also mix it with your hands, but if you do, wear rubber gloves to avoid chili powder burn.
Transfer the vegetable mixture to two 1-quart containers. Sprinkle 1/4 tsp of culture (or 1/4 cup of kefir whey) to each jar and then fill the containers with filtered water, leaving 2 inches of headspace to let the veggies bubble and expand as they ferment.
Seal the containers and let them sit on your kitchen counter, out of direct sunlight, for 3 days.
Check the vegetables every day to make sure they stay fully submerged in water. If they have risen above the water, simply push them down so they are fully covered by the water.
When the veggies are done fermenting, place them in the refrigerator.
Sprinkle with sesame seeds before serving.